A laser device having an improved resonator utilizes a single rigid base component for a light reflector coating that defines and forms the end terminals of the resonator cavity, means being provided for translating and reflecting the laser beam between linear light paths that respectively terminate at the mirror surfaces provided by the coating. Various embodiments are shown and in which one or more prisms are used to fold the laser beam between offset and parallel light paths. The end terminal forming mirror surfaces may be coplanar and face in a common direction in the base component, or the mirror surfaces may be provided on opposite side surfaces of the component. Where the base component is made from transparent material the terminals may also be defined by the inside and outside surfaces of the coating. The use of figured surfaces in the unitary structure is contemplated and the use of mirror clusters for folding the beam is also contemplated. The rigid base component may be provided by a prism, a solid state laser rod, the envelope for a fluid lasing medium or any suitable rigid unitary structure that has an appropriate surfaces arrangement for the contemplated use.

An improved folded cavity laser having particular application to holographic imaging is disclosed. The laser includes a lasing medium, such as for example a ruby rod, which is optically or electronically "pumped" in order to provide laser light. The medium includes first and second optical surfaces disposed at opposite ends of the lasing medium. A retro-reflecting roof mirror is disposed in optical alignment with the second optical surface of the lasing medium. A transverse mode selector is provided in optical alignment with the first surface of the lasing medium in order to surpress all transverse modes except those of a desired character. In the present embodiment, the transverse mode selector includes two apertures of approximately two millimeters diameter in order to obtain a laser output with a TEM.sub.00 mode. The use of a twin aperture transverse mode selector in conjunction with a retro-reflecting roof mirror provides at least twice the total cavity length and lasing medium than a conventional holographic pulsed laser, as well as two output beams which are in phase and coherent with each other. These beams may be directly used as an object and reference beam in a holographic system.

A single facet wobble free light scanner which eliminates the effects of wobble caused by bearing inaccuracies or other mechanical factors. A pentaprism, pantamirror, right angle prism or right angle mirror monogon 30 is rotated about an axis passing through its sides and through the axis of the applied light beam 8. By reflections off of two mirrored surfaces 22, 24, the output light beam 28 creates a plane of light. When, or if, the pentaprism 30 wobbles about the rotational axis, the effects of the wobble are eliminated because via the internal reflections of the pentaprism, the output light beam 28a is parallel to the original output light beam 28, the parallel light beams 28, 28a being focused onto the scan surface by external optics 70.

A single facet wobble free light scanner which eliminates the effects of wobble caused by bearing inaccuracies or other mechanical factors. A pentaprism, pentamirror, right angle prism or right angle mirror monogon 30 is rotated about an axis passing through its sides and through the axis of the applied light beam 8. By reflections off of two mirrored surfaces 22, 24, the output light beam 28 creates a plane of light. When, or if, the pentaprism 30 wobbles about the rotational axis, the effects of the wobble are eliminated because via the internal reflections of the pentaprism, the output light beam 28a is parallel to the original output light beam 28, the parallel light beams 28,28a being focused onto the scan surface by external optics 70.

A method and apparatus for producing preferential polarization of the output light beam from a laser of the kind having a three surface retroreflector comprises mounting the three reflecting surfaces of the retroreflector so that the surfaces are orthogonal in the retroreflector. The preferential polarization is obtained by controlling the combined effects of the orientation of the retroreflector assembly, with respect to the axis of the beam, and the selection of the coatings on the three reflecting surfaces.